For example, in a semiconductor manufacturing process, drying of the process has been rapidly advanced in recent years, and there has been employed a semiconductor manufacturing device such as a plasma etching device, a plasma CVD device, an ion implanting device, an ashing device, an electron beam lithography device, or an X-ray lithography device. In those devices, a sample such as semiconductor wafer has been frequently processed in a vacuum.
Also, as means for holding the sample in those devices, there have been proposed methods such as a mechanical chuck using a mechanical method, a vacuum chuck using a differential pressure from the atmospheric pressure, and an electrostatic chuck using an electrostatic adsorption force. Of those methods, the electrostatic chuck is advantageous in that the sample and a holder are held thermally uniformly and with high reliability.
Then, as one type of those electrostatic chucks, there has been employed a bipolar electrostatic chuck. The bipolar electrostatic chuck is made up of, for example, a first electrode that is a large part and forms a base, and a second electrode that is disposed on the first electrode and is of an annular configuration with a center opening. When a dc power supply is connected between the first electrode and the second electrode, and a sample such as a semiconductor wafer is mounted on a sample adsorption surface formed an upper surface of the first electrode and an upper surface consisting of the second electrode, the sample is absorbed and held by an electrostatic attractive force developed between a lower surface of the sample and the sampling adsorption surface.
In the above bipolar electrostatic chuck, the first electrode that forms the base generally has an electrode recess formed by subjecting its upper surface to mechanical processing, and the second electrode having the annular configuration is held within the electrode recess (for example, refer to JP 2610112 B, JP 2610113 B, JP 2614421 B, and JP 2614422 B). In the thus formed bipolar electrostatic chuck, a slight clearance is formed between the second electrode in which the electrode recess is disposed and the first electrode. Therefore, it is important to form the clearance with high precision for holding reliably the sample like a wafer with electrostatic adsorption force. In the bipolar electrostatic chuck, a corner of the electrode recess formed on the first electrode is rounded with a given radius curvature to a recess bottom surface (for example, refer to JP 2610112 B, and JP 2610113 B).
Also, as another example of the bipolar electrostatic chuck, a dc power supply is connected between an electrode member that is disposed in a recess groove defined in the vicinity of the center of a main member that forms the base and an outer electrode member that is disposed in a recess groove defined at an outer side of the vicinity of the center of the main member (for example, refer to U.S. Pat. No. 5,213,349).
However, in the bipolar electrostatic chuck of the type that forms the electrode recess in the upper surface of the first electrode and holds the second electrode in the electrode recess as described above, complicated mechanical processing that needs a high processing precision is required for forming a slight clearance between the electrodes and rounding the corner of the electrode recess. Likewise, in the electrostatic chuck of the type that form the recess groove in the vicinity of the center of the main member that forms the base and the recess groove at the outer side thereof, respectively, and connect the dc power supply to the two electrode members disposed in those recess grooves to form the bipolar type, the complicated high-precision mechanical processing is required in forming the above recess grooves and assembling the main member and the electrode member.
On the other hand, in the electrostatic chuck, an oxide coating is often formed on the surface of the electrostatic chuck for the purposes of protecting the electrostatic chuck from plasma exposure in the case where the electrostatic chuck is used in the plasma etching device, or functioning the oxide coating as a dielectric film. However, the oxide coating is corroded or reduced by an electrochemical action of ions, electrons and radicals contained in the plasma due to a long-time use in the plasma etching device. Also, in the operation of fitting or removing the electrostatic chuck in the semiconductor manufacturing device, the oxide coating such as the sample adsorption surface may be scratched by a tool in error. The above deterioration or scratch of the oxide coating of the electrostatic chuck causes the electrical isolation to be deteriorated to increase a leakage current between the bipolar, or causes the adsorptive force with respect to the sample such as the wafer to be deteriorated. For that reason, in the electrostatic chuck that has been deteriorated by use as described above, even if portions except for the oxide coating on the surface thereof are perfectly sound, the electrostatic chuck is scrapped as it is, or it is necessary to reproduce the oxide coating lost due to the deterioration or scratch if the electrostatic chuck is recycled without being scrapped.
In order to recycle the bipolar electrostatic chuck that has been used as described above, it is necessary to disassemble the bipolar electrostatic chuck once. In other words, in the bipolar electrostatic chuck of the type that has the second electrode disposed in the electrode recess of the first electrode, it is necessary to separate the second electrode from the electrode recess of the first electrode. Similarly, in the bipolar electrostatic chuck of the type that has the inner electrode member and the outer electrode member disposed in the recess groove formed in the vicinity of the center of the main member and the recess groove formed at the outer side, respectively, it is necessary to separate the respective electrode members from the main member. In the respective electrodes, the respective electrode members, and the main member, there has been required a recycle process in which an oxide coating is again formed after the oxide coating formed on the respective surfaces of those members is stripped once and the surfaces are then polished.
However, in the electrostatic chucks of any types, in order to remove the annular electrodes disposed in the recess of the electrode or the recess groove, a heat treatment must be conducted to break down an adhesive layer that fixes the annular electrode within the recess or the recess groove, or the annular electrode must be removed by mechanical means. Thus, there are many cases in which it is difficult to disassemble the bipolar electrostatic chuck that has been assembled once. Also, the configurations of the surfaces of the separated first electrode and main member onto which the second electrode and the electrode member had been fixed are complicated. As a result, a polishing process or an oxide coating reproducing process necessary for recycle is complex and diverse, and a large number of processing steps are required in order to use the electrostatic chuck again, thereby increasing the reproduction costs. Also, the reproduced oxide coating may lack the coating intensity on the boundary surface of the reproduced electrode, thereby leading to such a problem that the durability is deteriorated. In addition, even if various reproducing processes are conducted, the electrode that has been subjected to the respective processing required for reproduction increase the amount of reduced dimensions as compared with the electrodes that have not yet been reproduced. As a result, there arises such a problem that the electrode cannot be again used in the semiconductor manufacturing device even if the electrode is assembled as the electrostatic chuck again. For that reason, even if the electrostatic chuck is recycled, the number of times of reproductions is extremely restricted, and there are many cases in which it is substantially difficult to recycle the used electrostatic chuck.